libsanitizer/sanitizer_common/sanitizer_symbolizer_linux.cc

   1 //===-- sanitizer_symbolizer_linux.cc -------------------------------------===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is shared between AddressSanitizer and ThreadSanitizer
   9 // run-time libraries.
  10 // Linux-specific implementation of symbolizer parts.
  11 //===----------------------------------------------------------------------===//
  12 #ifdef __linux__
  13 #include "sanitizer_common.h"
  14 #include "sanitizer_internal_defs.h"
  15 #include "sanitizer_libc.h"
  16 #include "sanitizer_placement_new.h"
  17 #include "sanitizer_symbolizer.h"
  18
  19 #include <elf.h>
  20 #include <errno.h>
  21 #include <poll.h>
  22 #include <sys/socket.h>
  23 #include <sys/types.h>
  24 #include <sys/wait.h>
  25 #include <unistd.h>
  26
  27 #if !defined(__ANDROID__) && !defined(ANDROID)
  28 #include <link.h>
  29 #endif
  30
  31 namespace __sanitizer {
  32
  33 static const int kSymbolizerStartupTimeMillis = 10;
  34
  35 bool StartSymbolizerSubprocess(const char *path_to_symbolizer,
  36                                int *input_fd, int *output_fd) {
  37   if (!FileExists(path_to_symbolizer)) {
  38     Report("WARNING: invalid path to external symbolizer!\n");
  39     return false;
  40   }
  41
  42   int *infd = NULL;
  43   int *outfd = NULL;
  44   // The client program may close its stdin and/or stdout and/or stderr
  45   // thus allowing socketpair to reuse file descriptors 0, 1 or 2.
  46   // In this case the communication between the forked processes may be
  47   // broken if either the parent or the child tries to close or duplicate
  48   // these descriptors. The loop below produces two pairs of file
  49   // descriptors, each greater than 2 (stderr).
  50   int sock_pair[5][2];
  51   for (int i = 0; i < 5; i++) {
  52     if (pipe(sock_pair[i]) == -1) {
  53       for (int j = 0; j < i; j++) {
  54         internal_close(sock_pair[j][0]);
  55         internal_close(sock_pair[j][1]);
  56       }
  57       Report("WARNING: Can't create a socket pair to start "
  58              "external symbolizer (errno: %d)\n", errno);
  59       return false;
  60     } else if (sock_pair[i][0] > 2 && sock_pair[i][1] > 2) {
  61       if (infd == NULL) {
  62         infd = sock_pair[i];
  63       } else {
  64         outfd = sock_pair[i];
  65         for (int j = 0; j < i; j++) {
  66           if (sock_pair[j] == infd) continue;
  67           internal_close(sock_pair[j][0]);
  68           internal_close(sock_pair[j][1]);
  69         }
  70         break;
  71       }
  72     }
  73   }
  74   CHECK(infd);
  75   CHECK(outfd);
  76
  77   int pid = fork();
  78   if (pid == -1) {
  79     // Fork() failed.
  80     internal_close(infd[0]);
  81     internal_close(infd[1]);
  82     internal_close(outfd[0]);
  83     internal_close(outfd[1]);
  84     Report("WARNING: failed to fork external symbolizer "
  85            " (errno: %d)\n", errno);
  86     return false;
  87   } else if (pid == 0) {
  88     // Child subprocess.
  89     internal_close(STDOUT_FILENO);
  90     internal_close(STDIN_FILENO);
  91     internal_dup2(outfd[0], STDIN_FILENO);
  92     internal_dup2(infd[1], STDOUT_FILENO);
  93     internal_close(outfd[0]);
  94     internal_close(outfd[1]);
  95     internal_close(infd[0]);
  96     internal_close(infd[1]);
  97     for (int fd = getdtablesize(); fd > 2; fd--)
  98       internal_close(fd);
  99     execl(path_to_symbolizer, path_to_symbolizer, (char*)0);
 100     internal__exit(1);
 101   }
 102
 103   // Continue execution in parent process.
 104   internal_close(outfd[0]);
 105   internal_close(infd[1]);
 106   *input_fd = infd[0];
 107   *output_fd = outfd[1];
 108
 109   // Check that symbolizer subprocess started successfully.
 110   int pid_status;
 111   SleepForMillis(kSymbolizerStartupTimeMillis);
 112   int exited_pid = waitpid(pid, &pid_status, WNOHANG);
 113   if (exited_pid != 0) {
 114     // Either waitpid failed, or child has already exited.
 115     Report("WARNING: external symbolizer didn't start up correctly!\n");
 116     return false;
 117   }
 118
 119   return true;
 120 }
 121
 122 #if defined(__ANDROID__) || defined(ANDROID)
 123 uptr GetListOfModules(LoadedModule *modules, uptr max_modules) {
 124   UNIMPLEMENTED();
 125 }
 126 #else  // ANDROID
 127 typedef ElfW(Phdr) Elf_Phdr;
 128
 129 struct DlIteratePhdrData {
 130   LoadedModule *modules;
 131   uptr current_n;
 132   uptr max_n;
 133 };
 134
 135 static const uptr kMaxPathLength = 512;
 136
 137 static int dl_iterate_phdr_cb(dl_phdr_info *info, size_t size, void *arg) {
 138   DlIteratePhdrData *data = (DlIteratePhdrData*)arg;
 139   if (data->current_n == data->max_n)
 140     return 0;
 141   InternalScopedBuffer<char> module_name(kMaxPathLength);
 142   module_name.data()[0] = '\0';
 143   if (data->current_n == 0) {
 144     // First module is the binary itself.
 145     uptr module_name_len = internal_readlink(
 146         "/proc/self/exe", module_name.data(), module_name.size());
 147     CHECK_NE(module_name_len, (uptr)-1);
 148     CHECK_LT(module_name_len, module_name.size());
 149     module_name[module_name_len] = '\0';
 150   } else if (info->dlpi_name) {
 151     internal_strncpy(module_name.data(), info->dlpi_name, module_name.size());
 152   }
 153   if (module_name.data()[0] == '\0')
 154     return 0;
 155   void *mem = &data->modules[data->current_n];
 156   LoadedModule *cur_module = new(mem) LoadedModule(module_name.data(),
 157                                                    info->dlpi_addr);
 158   data->current_n++;
 159   for (int i = 0; i < info->dlpi_phnum; i++) {
 160     const Elf_Phdr *phdr = &info->dlpi_phdr[i];
 161     if (phdr->p_type == PT_LOAD) {
 162       uptr cur_beg = info->dlpi_addr + phdr->p_vaddr;
 163       uptr cur_end = cur_beg + phdr->p_memsz;
 164       cur_module->addAddressRange(cur_beg, cur_end);
 165     }
 166   }
 167   return 0;
 168 }
 169
 170 uptr GetListOfModules(LoadedModule *modules, uptr max_modules) {
 171   CHECK(modules);
 172   DlIteratePhdrData data = {modules, 0, max_modules};
 173   dl_iterate_phdr(dl_iterate_phdr_cb, &data);
 174   return data.current_n;
 175 }
 176 #endif  // ANDROID
 177
 178 }  // namespace __sanitizer
 179
 180 #endif  // __linux__